Lead Balls Research Articles

In-operation performance evaluation of damped light poles using fatigue life estimations

This study demonstrates the practical application of vibration-based monitoring for the health evaluation of slender structures. The subject structures are the light poles installed on the Confederation Bridge in eastern Canada. The unique nature of this 12.9 km bridge and its location in the Northumberland Strait provides an opportunity to study light pole vibrations in harsh environmental conditions. In a previous study, a prototype impact damper using two lead balls within a pipe cylinder added to the top of the pole was developed to attenuate the large amplitude first-mode vibrations. In this current study, an extended full-scale vibration monitoring program of two bridge light poles under actual wind loading conditions is carried out over a period of several months to evaluate the in-operation performance of the custom prototype pole-top impact damper. An analysis method for calculating the cumulative fatigue damage (cFD) from vibration data and for estimating the remaining fatigue service life of in-operation bridge light poles is presented. With these methods, it is found that the pole-top impact dampers increase the remaining fatigue service life of the original Confederation bridge light poles by approximately 2.5 years. From fatigue modeling, it is also found that if the dampers had originally been installed with the light poles during construction in 1997, the cumulative fatigue damage could have been reduced by an average of 25% with a projected service life increase of 48%, which represents an additional 12 years of service above the actual estimated service life of 25 years.

Experimental and Analytical Determination of the Coefficient of Dynamic Loading in the Contact Interaction of Bodies

The calculation of the coefficient of dynamism of the contact interaction of bodies (lead balls and wheat grains with a moisture content of 11.5%) was carried out based on the hypothesis of equality of the work consumed during static and dynamic deformation of bodies, according to the formula:Θ=(So+Su)/(Sod+Su),where So – residual deformation of the body under static loading;Sod – residual deformation of the body under dynamic loading;Su – elastic deformation under static and dynamic loading.The components of the formula were determined on specially designed devices:– on an electromechanical press with static interaction of bodies, at a deformation rate of 0,055 m/s, the following values were determined from the load – discharge diagrams: the value of elastic deformation Su and the maximum residual deformation of bodies So.– on a vertical copra (at a contact interaction speed of 1-2 m/s) and a shock stand (at an impact speed of 11-15 m/s), the residual Sod deformation was determined by the size of the contact spot on the bodies after the impact.The calculated values of the dynamism coefficient were:for lead balls – 1,4-2,1;for wheat grains – 1,3-1,45.The results obtained indicate that the value of the dynamism coefficient increases with increasing impact velocity, with the same work spent on deformation, since the proportion of residual deformation in the total deformation of bodies decreases (bodies are strengthened).It is advisable to continue experiments to determine the coefficient of dynamism of bodies depending on the impact velocity, the configuration of the impact surface and the physical properties of the contacting bodies.

Franceses contra británicos en el puente de Marialba. Historia y arqueología de un episodio de la Guerra de la Independencia en Gallegos de Argañán, Salamanca

En 2018 se ejecutó la II Fase del proyecto de investigación Campos de Batalla en Gallegos de Argañán, Salamanca, ss. XVII – XIX, basada en la prospección intensiva de grandes áreas mediante detector de metales. Se han documentado varios miles de objetos metálicos y en concreto, una gran concentración de proyectiles esféricos en torno al puente de Marialba. La investigación histórica ha permitido vincular esos hallazgos con un episodio ocurrido entre tropas británicas y francesas, el 23 de abril de 1811, poco antes de la batalla de Fuentes de Oñoro. Las concentraciones de disparos de diferentes calibres permiten identificar los emplazamientos de las tropas sobre ambas orillas. Al mismo tiempo, los diferentes grados de deformación que presentan los proyectiles podrían ser indicadores de la distancia a la que se realizaron los disparos y por consiguiente, de la intensidad de la lucha en cada lugar.

Method for determining dynamic coefficient of friction of bodies

To study the effect of the material and the roughness of the impact surface, the velocity of impact interaction and the properties of bodies on the value of the dynamic coefficient of friction, a shock testing machine is proposed that provides an impact contact effect on the bodies in a plane located at an angle adjustable from 0 to 45 ° relative to the normal line drawn to the point of impact, in the range of speeds from 12 to 72 m/sec. It is found that at an impact velocity of 25 m/sec with an increase in the angle of inclination of the impact steel plane, the angle of friction and the corresponding dynamic coefficient of friction increase in a linear relationship. The maximum values of angles φ and dynamic coefficients of friction f make: - for steel balls φ = 8.3°, f = 0.146; - for lead balls φ = 11.4°, f = 0.167; - for grains of the wheat φ = 6.8°, f = 0.12. The results obtained indicate that the elastoplastic properties and shape of the bodies do not have any significant effect on the angles of reflection of bodies from the impact plane.

Overview of theoretical considerations and problems related to the putative existence of repulsive gravitation, charge-mass repulsive force and unification

We use a torsion balance scale to measure the attraction between two large lead balls and two smaller brass balls, connected with an up-side down T bar that is hung with a string. The vertical part of the T bar is attached with a mirror that reflects a laser beam to provide a light spot that shows how much the T bar has turned. It is observed that the gravitational forces between the lead balls and the brass balls are reduced when the temperature of the lead balls increased. Thus, this experiment shows clearly the existence of a repulsive gravitational force that increases as the temperature of the lead balls increase. This supports that the charge-mass interaction is the reason that the theories of Galileo, Newton, and Einstein failed to explain the Anomaly of the Space-Probes and flybys, and the fact that not all the neutral subjects necessarily fall with the same acceleration. In other words, the Newtonian law of gravitation is only approximately valid. Thus, the attempts such as J. Luo (罗俊)’s to obtain an accurate gravitational coupling constant with just improved skill are futile. The physical picture of Galileo, Newton, and Einstein on gravitation needs extension beyond the Standard Model (SM).

A Suit for the Physical Training: Application and the Value of Innovation

By recognizing the sequential body configuration and time shifts, it is possible to calculate the dynamic moment of inertia. Body, arm, and leg models were proposed in which possible configurations and influential mass distribution sizes were studied. Described is the choice of optimal models for modeling dynamic moments of inertia which are represented as the best approximation for the dynamic moment of inertia in a dynamic sense. Dynamic and physiological parameters (aerobic, aerobic-anaerobic and anaerobic stimuli) are load indexes based on the geometric progression of the metabolic processes (aerobic - index 3, aerobic-anaerobic – index 6 and anaerobic – index 12). For this purpose, the QBASIC program was used to calculate the weight gain for individual segments according to load indexes (index – 3, 6 or 12). A weight gain calculation program for individual segments according to load indexes of male and female bodies was used to calculate the mass, volume and thickness of silicone with and without the addition of lead balls or lead dust. The training process suit represents a three-layer suit where the suit layers are as follows: the first layer (Lycra) which adheres directly to the skin and which must have an elasticity factor that will satisfy the required flexibility and moisture absorption; the second layer (Silicone) the weight of which is proportionately distributed so that the weight of each segment of the second layer corresponding to each individual body segment is equal to the weight gain for that particular body segment; the third layer (Lycra) which is an outer layer and which is watertight but at the same time passes moisture outwards and is elastic. On this basis, a three-layer suit was made with proportionally distributed loads per individual body segments, which ensures proportional load of the segments and the whole body. Thus applied stimuli provide an even impact on the development of the musculoskeletal nervous system in the direction of the development of motor potentials at a high correlation level in the coordination of body motion in the chosen activity. Application, testing and measurement of the suit performance in certain sport movements (walking, running, pedaling, rowing, volleyball and basketball) were carried out using the POLAR measuring instrument and heart beat frequencies depending on intensity of the load were obtained. Based on the information obtained, the Training Process Suit can be used for sports training, recreational activities and for medical purposes when carrying out physical therapy.

Movements of the lumbo-sacral nerve roots in the spinal canal induced by straight leg raising test: an anatomical study.

The pain involved in the herniated discs could be generated by some mobility of the nerve roots during straight leg raising (SLR). SLR produces some movement of nerves, but the magnitude of this displacement needs to be thorough, that is why we have investigated lumbo-sacral nerve root displacement in the spinal canal during the passive straight leg raise (SLR). Fourteen cadavers underwent laminectomy to mark the nerve roots of L2-S1 with lead balls. X-rays were taken during different movements imposed on the body: bilateral hip extension, left SLR then right and bilateral SLR. By superimposing these images two by two, the displacement of the nerve roots is quantified numerically during the various SLR maneuvers with respect to the reference position corresponding to the bilateral hip extension. The median range of the different nerve root movements ranged from 0.10 to 0.51cm (p < 0.05 except for the L2 root) when the left SLR is applied, from 0.26 to 0.48cm (p < 0.05) with the right SLR and from 0.30 to 0.65cm (p < 0.05) with a bilateral SLR. No statistically significant relationship was found between age and movement value. The lumbo-sacral nerve roots in the spinal canal region move statistically significantly in response to the clinically applied SLR test, except for L2 root during the left SLR. This movement is symmetric and greater when a bilateral SLR is applied. These anatomical results are correlated with those observed empirically in clinical practice.

ДЕФОРМАЦИОННЫЕ СВОЙСТВА НАСЫПНОГО СЛОЯ ИЗ СВИНЦОВЫХ ШАРИКОВ

The results of a static investigation of the compression of granular layers from metal balls are presented. Metal balls are a promising damping element of the protective structures from explosive and impulse actions. With intensive actions, the granular layers deform irreversibly. Static compression of a filling medium was done at the Zwick Amsler HA 100 test machine. An experimental deformation diagram was obtained for uniaxial compression of a granulated layer of lead balls under static loading in a wide range of loading values up to the liquidation of free porosity. The diagram has a nonlinear and irreversible character. Loading of symmetric fragments of the layer has been numerically modeled for two versions of regular packing of the balls - tetrahedral and cubic. In both versions developed plastic flow of the material, filling the pores up to complete compaction, is observed. The numerical deformation diagrams, similar to the experimental ones, are strongly nonlinear and irreversible. The behavior of the experimental curve qualitatively corresponds to that of the numerical curves. This curve in the range between the deformation curve of the filling layer with tetrahedral and cubic ideal packing of the balls. Numerical modeling revealed that the zones of abrupt increase of resistance of the porous material are connected with liquidation of free porosity. Keywords: layer of balls, porous medium, experiment, static deformation, compression, nonlinearity, irreversibility, numerical modeling.

Determination of Unit Pressure Force in Material Volume in the Course of Refractory Stamping Press Moulding

Abstract The paper presents results of assessment of the unit pressure force within the refractory material volume in the course press-moulding of stampings for refractory precast shapes. The force was evaluated with the use of physical simulation of deformation undergone by lead balls placed in the raw refractory mass subjected to pressing in a metal die. To determine the value of unit pressure force applied to the aggregate grains in the course of stamping press-moulding, physical model of deformation of a sphere induced by the uniaxial stress state was used.

An Improved Method for Calibrating the Gantry Angles of Linear Accelerators

Linear particle accelerators (linacs) are widely used in radiotherapy procedures; therefore, accurate calibrations of gantry angles must be performed to prevent the exposure of healthy tissue to excessive radiation. One of the common methods for calibrating these angles is the spirit level method. In this study, a new technique for calibrating the gantry angle of a linear accelerator was examined. A cubic phantom was constructed of Styrofoam with small lead balls, embedded at specific locations in this foam block. Several x-ray images were taken of this phantom at various gantry angles using an electronic portal imaging device on the linac. The deviation of the gantry angles were determined by analyzing the images using a customized computer program written in ImageJ (National Institutes of Health). Gantry angles of 0, 90, 180, and 270 degrees were chosen and the results of both calibration methods were compared for each of these angles. The results revealed that the image method was more precise than the spirit level method. For the image method, the average of the measured values for the selected angles of 0, 90, 180, and 270 degrees were found to be -0.086 ± 0.011, 90.018 ± 0.011, 180.178 ± 0.015, and 269.972 ± 0.006 degrees, respectively. The corresponding average values using the spirit level method were 0.2 ± 0.03, 90.2 ± 0.04, 180.1 ± 0.01, and 269.9 ± 0.05 degrees, respectively. Based on these findings, the new method was shown to be a reliable technique for calibrating the gantry angle.

Low frequency pressure waves in a vapor-liquid medium with a fixed layer of spherical particles

The features of the propagation of low-frequency pressure waves in a liquid-vapor flow through a layer of close-packed spherical solid particles have been studied. Principal measurements have been performed at two pressure values, mainly 0.2 and 0.6 MPa; in a cylindrical channel using lead balls sized 3 and 8 mm. The experimental results allowed defining the characteristic parameters and conditions providing that the wave’s propagation velocity coincides with the thermodynamic equilibrium’s acoustic speed in the vapor-liquid mixture. The results show the dispersive nature of the acoustic speed in the vapor-liquid medium.

Separation of impurity in molten metals by using superconducting magnet

The separation method by using electromagnetic force is receiving particular attention as elimination method of impurities in molten metal. In this study, low-melting metal is used as model metal and the relation between electromagnetic force and motion of the particle in molten metal was discussed by calculation and experiment. As the result of calculation, the relation between electromagnetic force and separation efficiency can be obtained. The electromagnetic separation was experimented in the condition that was estimated from the results of calculation (average flow velocity: 0.4 m/s, magnetic flux density: 10 T, electric current density: 3.3E+4 A/m 2). It succeeded that insulating lead balls in low-melting metal were separated by electromagnetic force.

超電導磁石を利用した電磁分離装置開発の検討

The separation method using electromagnetic force is receiving attention as an elimination method for the removal of impurities from molten metal. In this study, the relation between electromagnetic force and the motion of particles in molten metal was discussed through experiment and calculation using metals with low melting temperatures. Electromagnetic separation was examined under conditions which were decided by the results of calculations (average flow velocity: 0.1 m/s, electric current density: 2.1×104 A/m2, magnetic flux density: 10 T).The relation between particle size and separation efficiency can be obtained through calculation. It was successfully demonstrated that the insulating lead balls in metals melted at low temperature could be separated by electromagnetic force.

Osteological evidence for the Battles of Zürich, 1799: a glimpse into soldiery of the past

AbstractFour human skeletons probably could be attributed to people killed during the Battles of Zürich in 1799. Cranial and postcranial gunshot wounds are consistent with those made by black powder weapons using lead balls as ammunition. Additional finds include a probable case of Scheuermann's Disease and a pipe smoker's facet. Copyright © 2003 John Wiley &amp; Sons, Ltd.

Low-frequency soundproof concrete

A low-frequency soundproofing concrete has been developed. In this type of concrete, lead spheres coated with silicone rubber are used as aggregates, the lead ball being heavy and rigid, and the silicone rubber light and soft. The coated lead spheres are uniformly embedded into a short fibre reinforced cement-based matrix. When a sound wave approaches such a concrete panel, localised excitation in the coated lead balls will be induced at certain frequencies. Resonant excitation can consume a considerable amount of energy and thus the sound transmission through the panel at these frequencies can be greatly reduced. Experimental results show that concrete with the embedded coated lead spheres produces resonance at about 150 Hz and also improves the sound insulation at the low frequency range.

Low-frequency soundproof concrete

A low-frequency soundproofing concrete has been developed. In this type of concrete, lead spheres coated with silicone rubber are used as aggregates, the lead ball being heavy and rigid, and the silicone rubber light and soft. The coated lead spheres are uniformly embedded into a short fibre reinforced cement-based matrix. When a sound wave approaches such a concrete panel, localised excitation in the coated lead balls will be induced at certain frequencies. Resonant excitation can consume a considerable amount of energy and thus the sound transmission through the panel at these frequencies can be greatly reduced. Experimental results show that concrete with the embedded coated lead spheres produces resonance at about 150 Hz and also improves the sound insulation at the low frequency range.

The internal form of compacted ceramic components: a comparison of a finite element modelling with experiment

This paper is concerned with the internal form of compacted ceramic green components. The structural inhomogeneity of alumina specimens, compressed in a top pressed cylindrical die, is studied experimentally, by using lead balls as tracers to detect the densification, as well as by numerical computation. The flow behaviour of a ceramic powder, an agglomerated alumina, is described by the modified Drucker-Prager/cap elasto-plasticity material model developed for powder applications. The modified Drucker-Prager/cap constitutive model, implemented by using the finite element code ABAQUS, is discussed. The procedure for selecting the necessary material parameters by the inclusion of material response data and assumptions made in the implementation of the numerical model are described. The accuracy of the presented numerical method is evaluated by comparing the simulation results with experimental data obtained from density measurements. The evolution of the density distributions during the entire compaction process is predicted. The determining step for the formation of the subtle density variations on the central axis of the green ceramic compacts was found, from the modified Drucker-Prager/cap finite element analysis, to be the unloading step of the compaction process. In this respect, a comparison of the finite element and experimental results showed good mutual agreement.

Transfert de chaleur dans un régénérateur thermique à basse température

The heat transfer in a low temperature regenerator is determined by correlating the experimental results with the mathematical pattern that describes the transitory process. The regenerator was filled with lead balls with an initial temperature of 80 K, hydrogen gas at 2 bar, with a variable flow capacity of 2 to 10 Nm 3.h −1. The heat transfer, according to the tests, is defined in the following non-dimensional relation Nu = 0, 825 Re 0,48 Pr 1 3 .

Radio-anatomic position for the lateral radiographic view of the human patello-femoral joint.

Recent clinical and epidemiological studies have emphasised the importance of the patello-femoral joint (P-FJ) in osteoarthritis. X-ray examination of this joint for joint space width (JSW) assessment using the standard medio-lateral view is difficult. In 26 femora, the mean angle of inclination between the medial and lateral condyles measured at their inferior and anterior surfaces, relative to a line passing between the medial and lateral femoral epicondyles, was used to define the optimum alignment of the x-ray tube. The results showed that for medio-lateral radiography of the P-FJ, the central ray of the x-ray beam should be directed cranially, in a upward projection by 5 degrees and then anteriorly by 4 degrees, resulting in superimposition of the inferior and anterior condylar surfaces respectively. The value of these angles was confirmed by radiographs of the 26 femora and 10 post mortem joints. The margins for joint space width measurement were identified by embedding lead balls, within the cartilage of the cadaveric knees, and were defined as the median vertical ridge of the patella and the middle of the patella groove on the femur.

Models for Inelastic Deformation of Particles Associated With Hot Pressing of Metal Matrix Composites

During fabrication of fiber reinforced metal-matrix composites by hot pressing, fiber breakage due to particles impingement during consolidation of fiber/particle system is very common. In studying the fiber breakage, one of the main issues is the interactions between fibers and particles during consolidation. In this study, we proposed to investigate the problem of fiber/particle interactions by examining a unit problem consisting of a deformable particle and a cylinder. A rather engineering model for axisymmetric deformation of a particle induced by a rigid sphere was developed first and then extended to the interactions between a deformable particle and a rigid cylinder. The calculations were compared with experiments on lead balls, good agreement was observed. The model was then applied to determining the maximum bending stress in fibers using the simple beam theory. A safe criterion for preventing fibers from breaking was found.